I imagine

That unlike his brother, Giles Grimm isn’t blind to the whole Badwolf/Red Riding hood. He notices things such as Badwolf not being nearly as hard on Cerise as other students. He takes notice of things such as when Parent/teacher conferences happen, Red Riding Hood lingers just a little bit more longer in the classroom with Badwolf.

Giles Grimm notices these things, yet he always makes sure that others may not push any buttons, at least until the family is ready. He could be seen pushing Milton Grimm out of the room if he begins to ponder a little too much of a “charater hanging out with their villain a little too long”